Railway signaling apparatus



`Iune 10, 1947. F. T. PAscoE ET Al.

RAILWAY SIGNALING APPARATUS 5 Sheets-Sheet 1 Filed June. 25, 1945 INVENTORS. n Fpamli TPaf'eoe and B Y AplzupLL/pome.'

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satfenteci .une 1G, 1947 RAILWAY SIGNALIN G APPARATUS Frank T. Pascoe, Carnegie, and Arthur L. Jerome, Edgewood, Pa., assignors to The Union Switch & Signal Company, Swssvale, Pa., a corporation of Pennsylvania Application June 23, 1945, Serial No. 601,100

13 Claims.

Qur invention relates to railway signaling apparatus and particularly to improved means for governing movement of trafiic in track stretches by centralized trafiic control.

Track stretches governed by C. T. C. from a remote control office are frequently equipped with wayside apparatus comprising a system of reversible circuits governed by traffic conditions in the stretch, While the system of circuits for each stretch is manually controlled from the oiiice so as to at times prepare the stretch for tra-flic in one direction and to at other times prepare the stretch for trac in the other direction. These circuits govern the wayside signals which control movement of traine into and through the stretch and also control the transmission of indications to the oiiice to show whether or not the stretch has been prepared for traffic in the` desired direction and to also indicate occupancy of the stretch.

In some C. T. C. installations traffic locking circuits are provided in the C. T. C. machine to prevent interference with traiilc in a stretch unless conditions are proper. These traffic locking circuits are governed by the indications received from the field stations at the ends of each stretch, and in order to insure proper functioning of the trafiie locking circuits, it is essential after a change in the direction of trailic in a stretch that indications be transmitted to the cnice to show that the sretch has been prepared for traffic.

The indication codes sent from a field station to the oiice may be delayed because of the use of the C. T. C. line circuit by control codes or by indication codes from other eld stations, and after a stretch has been prepared for traine a train may enter the stretch before an indication can be sent to the oflice to show that'the stretch has been prepared for traiic in the designated direction. The systems heretofore available have operated so that occupancy of the stretch prevents the block clear indication from being sent to the oiiice so that under these conditions the traffic locking circuits in the C. T. C. machine may not function as intended to cause the wayside equipment to maintain the established direction of trahie in a stretch during occupancy of the stretch.

An object of this invention is to provide means for insuring that after establishment of traiiic in a stretch an indication of this fact is certain to be transmitted to the oiiice even though a train enters the stretch before the indication is transmitted to the office.

Another object of the invention is to provide block indication means which is arranged so that the means which insures transmission of indications of occupancy of the detector section at the end of a stretch also insures transmission of block clear indications.

A further object of the invention is to provide improved indication means arranged so that at each eld station a single relay serves to insure transmission of indications of the occupied condition of a detector section and of the unoccupied condition of a track stretch.A

Another object of the invention is to provide improved means for insuring that the trafiic locking circuits in a C. T. C. machine will be effective regardless of delays in the transmission of indications from the field stations to the ofce.

A further object of the invention is to provide improved means for controlling the block indication lamp in a C. T. C. machine so as to prevent lighting of this lamp because of changes in either the oflice or the wayside equipment incident to a change in the direction of traiic in the track stretch with which the lamp is associated, but to insure lighting of this lamp during occupancy of the stretch.

Other objects of the invention and features of novelty will be apparent from the following description taken in connection with the accompanying drawings.

We shall describe one form of railway signaling apparatus embodying our invention and shall then point out the novel features thereof in claims.

In practicing our invention We provide at each end of the stretch a block indication relay having a pick-up circuit governed by the Wayside signal apparatus so as to be picked up when the stretch is prepared for traiiic and is unoccupied. When an end of the stretch is conditioned to be the entrance end, a stick circuit is provided for the block indication relay at that end of the stretch to keep the relay energized during occupancy oi the associated detector track section, or during release of the indication stick relay for the detector section track relay, to thereby insure that once the block indication relay at the entrance end of a stretch is picked up it will not be released following entrance of a train into the stretch until an indication code has been sent to the office showing that this indication relay is picked up. The equipment at the office includes indication relays governed from the eld stations at the ends of the stretch, and also includes a stick relay which is picked upv when a change in maaier l s the designated traffic direction in a stretch is initiated, while this relay remains picked up until indications are received that the new direction of traic has been established. The stick relay at the oiiice controls traic locking circuits in the C. T. C. machine to maintain the operators control of traic until a new direction of trac is established, and as the equipment in the field is arranged to insure that, when the wayside equipment establishes trafiic in the stretch, an indication of this fact will be transmitted to the ofiice, the stick relay at the office is certain to release and discontinue its control of the traiiic locking circuits so that these are thereafter subject to traiic conditions in the stretch.

1n addition, the stick relay at the office, when picked up, interrupts the circuits governed by the block indication relays for lighting the block indication lamp to thereby prevent lighting of this lamp as a result of changes in either the C. T. C. machine apparatus or the wayside apparatus incident to a change in the direction of traiiic in a stretch. This stick relay contact may be included in this lamp circuit since the relay is certain to release following establishment of traic in the stretch with the result that this lamp iscertain to be lighted during occupancy of the stretch.

In the drawings,

Figs. 1A and 1B when placed together with Fig. 1A at the left form a diagram of a stretch of single track railroad equipped with wayside apparatus embodyingour invention, and

Fig. 2 is a diagram showing C. T. C. machine circuits for use in connection with the apparatus shown in Figs. 1A and 1B.v v

Referring to Figs. 1A and 1B of the drawings there is shown therein a stretch of single track railway extending between two passing sidings and provided with wayside signal apparatus for authorizing trafiic to lmove in one direction through the stretch at times and to move in the other direction at other times. In this application only the portions of the wayside apparatus Aessential' to the understanding of this invention have been shown and the remainder of the apparatus may be arranged as shown in application for Letters Patent of the United States, Serial No. 501,264 of HS. Young, filed September 4, 1943.V

The equipment at theleft-hand or west end of the stretch includes a C. T. C. system eld'station unit designated station I-2, and the equipment at the right-hand or east end of the stretch includes a C. T. C. system neld station unit desighated station 3 4.

The field stations are connected with the oflice over a pair of line wires, not shown, by a code communication system which may be of thetype shown in Letters Patent of the United States No. 2,229,249, issued January 21, 1941 to L. V. Lewis, or in application for Letters Patent of the United States, Serial No. 496,907, iiled July 31, 1943, by A. P. J ackel, and described in Manual 506A of The Union Switch and Signal Company, Swissvale, Pa.

Consideration of the detailed mode or operation of the code communication system is not needed for an understanding of our invention and it is deemed sufficient to point out that a iield station is provided at each end of each track stretch to be controlled and that coding units are provided at the oice and at each field station and are connected by a pair of' line wires, not shown, over which control codes are transmitstation only is energized to effect temporary establishment of seven control channels between the oiiice and the station. The different stations have different code calls, consequently the selector relays for different stations or panelsare not energized at the same time, and the same channels provide communication at different times with all of the stations.

f The explanation of this invention requires only three channels employed in the transmission of control codes and ve channels employed in the transmission of indication codes, and in order to simplify the disclosure the other channels and Y related apparatus have not been shown;

The channels employed in the transmission of control codes are designated 2, 5 and l, and the channels employed in the transmission of indication codes are designated Il), I2, I3, I4 and I5, the numbers employed to designate these channels being the same as are employed to designate* theI corresponding channels in the above-identi-V fied application of I-I. S.l Young.

It is to be understood that the system of our invention is made up of a number of unit Yportions generally similar to the one shown in the drawings, but as the invention may be fully` understood from one such portion, only one has been illustrated in the drawings.

The oice and eld stations and wayside signal locations are each provided with a suitable source of direct current, such as a Storage battery, not shown, the terminals of which are designated B and C in the drawings.

In most instances in the drawingsY the' relay contacts are located directly under the winding of the associated relay, but in some cases in or- Vder to simplify the drawings, relay contacts are separated from the relay winding, and in these instances the relay with which the contacts are associated isvdesignated by appropriate reference characters placed above the contacts.

The equipment at each eld station includes a 4 `detail in the above-identified application of A. P.

J ackel.v The iield station starting relays FST are of the polarized type and eachv has contacts which Ynormally occupy their left-hand or normal positionfrom which they are moved to their righthand or reverse position to initiate transmission of an indication code, while the relay contacts f tion in consequence of the transmission of an indication code by the associated field station.

The indication relays at the oilice governed from the eld station I-2 at the left-hand or west end of the single track stretch include a relay ITK which is controlled by the track relay ITR for section IT; a signal indication relay ZRHK governed by relay 2RRGP which repeats the stop indications of the signals 2BA and 2R13; and a block indication relay ZRBK controlled by the relay ZRBP which in turn is governed by trafc conditions in the stretch as explained below.

The relays at the eld station 3--4 at the righthand end of the single track stretch function in a ysimilar manner to control the relays BTK, 4LHK and IILBK at the oiiice.

The block indication lamp BKE in the track diagram of the control machine is governed by the relays ZRBK and 4LBK, one of Which indicates the condition of occupancy of a portion of the single track stretch and the other of which indicates the condition of occupancy of the remainder of the single track stretch. The lamp BKE is also controlled by the indication relays ITK and 3TK for the detector sections at the ends of the stretch, and by the block indication repeater or auxiliary relay 2-4BKSR as hereinafter explained.

The signal levers 2SIG and 4SIG on the panel of the control machine are the usual three-position levers for the code control of the signal control relays at the field stations at the opposite ends of the stretch. The levers ZSIG and IISIG are electrically interlocked with respect to the control of train movements into the intervening single track stretch by the master directional polarized relay 2-4LP, as in the above-identified application of I-I. S. Young, and also in his Letters Patent of the United States No. 2,326,991. The relay 2-4LP' has associated therewith relays 2-4LPS and Z-JIBKSR which are governed substantially in the manner explained in detail in application for Letters Patent of the United States, Serial No. 567,188, led by us on December 8, 1944.

The equipment is arranged so that, when energy is applied to channel 2 and a control code is transmitted to a eld station, the traffic direction relay FS at that station is operated to condition the wayside apparatus to make that end of the stretch an exit or leaving end. Similarly, the

Aequipment is arranged so that', when energy is not applied to channel 2 and a control code is transmitted to a field station, the traino direction control relay FS is operated to condition the wayside apparatus to make that end of the stretch an entrance end so that the signal at that point may be controlled by the wayside circuits on operation of the associated signal relay.

The equipment is also arranged so that, when energy is supplied to the code channel governing a signal control relay such as, for example, channel 5 or 'I, and a control code is transmitted to a field station, the signal control relay at that station is operated to render the signal subject to the control of the wayside circuits.

The signal levers ZSIG and 4SIG are of the three-position type and each has a center position N, a left-hand position L, and a right-hand position R.. The levers control contacts which are shown diagrammatically in the drawings; the contacts which are closed in the left-hand position of the lever being designated L; those which are closed in the right-hand position of the lever being designated R; those which are closed in 'either the vnormal or the left-hand position o'f the lever being designated NL; and those which are closed in either the normal or the right-hand position of the lever being designated NR.

The equipment at each field station includes a relay MSP, not shown, the contacts of which are picked up when the contacts of the associated starting relay FST are reversed to initiate transmission of an indication code and when picked up remain picked up until transmission of the indication code is complete.

The equipment is shown in the condition which it assumes when the track stretch is vacant, the signals 2R and 4L are at stop, and the wayside signaling apparatus prepares the stretch for Westbound trafflc, that is, governs the westbound intermediate signals 5L and 6L in accordance with traffic conditions in advance, and also controls relay ILHD in accordance with traiiic conditions in advance so that signal 4LA or liLB may be cleared on reversal of the signal control relay LI-IS. In addition, it is assumed that signal 2L is at stop so the relay 2LPC is released as this relay is governed by signal 2L and is released when signal 2L is at stop and is picked up when this signal is at caution or clear. At this time the contacts 20 and 2I of the traffic directional relay ZWFSR at the left-hand or west end of the stretch are in their left-hand or normal positions and connect the line wires 23 and 24 over contacts 25 and 26 of relay ZLPC to a source of energy in series with an approach relay 2RAR. The energy supplied to the line wires 23 and 24 feeds over front contacts of track relays ITR, 2TH. and ATR., over back contacts 2'! and 28 of relay ERPC, and back contacts 30 and 3| of relay 5RSR to the winding of signal 5L and causes this signal, when lighted, to display its yellow or caution indication. The energy supplied to line wires 23 and 24 through the winding of relay 2RAR keeps contact 33 of the relay picked up so that it establishes the circuit including normal polar contact 32 of relay ZWFSR for energizing relay ZRBP and its contact 34 is picked up to interrupt the circuit leading to terminal I4 of the C. T, C. field station unit so that indication codes sent to the ofce cause the contacts of relay ZRBK to occupy their normal or released position, l

At this time signals 2RA and ZRB are at stop so the circuit of relay ZRRGP is complete and its contact 35 interrupts the supply of energy to terminal I5 of the C. T. C. system iield station unit, and, as section IT is vacant, contact 36 of track relay I TR is picked up and establishes the circuit of relay ITKS so that it is held in its energized or normal position by energy supplied over its front contact 31 and contact 38 of relay ITKS interrupts the circuit leading to terminal I0 of the field station unit. Accordingly, indication codes sent to the oce from this station release the relays 2RHK and ITK.

As signal 5L is conditioned to display its yellow indication, energy is supplied over back contact G and front Contact Y of the signal to relay 5LPC and its contacts are picked up to cause energy of normal polarity to be supplied to line wires il and 4I leading to the signal 6L. At this time wire @EI is connected to terminal C of a source over front contact 42 of relay SLPC and wire d@ is connected over front contact 43 of relay SLPC, front contact 45 of relay RTR, winding cf relay '.iLAR and back contacts Y and G of signal 5R to terminal B of the source. The energy supplied to signal 6L causes it, when lighted, to

display its green or clear indication, while energy is supplied over back contact Y and front contact G of the signal 6L to relay GLPC with the result that itsv contacts are picked up .and cause energy Y of normal polarity to be supplied to line wires 48 and 49 over a circuit similar to that described abovefor line wires M3 and 4I. This 'circuit includes in series therewith the approach relay BLAR.k

The energy supplied to line wires 48 and 49 is supplied over contacts i) and 5| of relay EFSR in their right-hand or reverse position to a polar relay iLHD to pick up its neutral contacts and to cause its polar contacts to occupy their lefthand or normal positions so that polar contact 53 and neutral contact 54 .provide a circuit for relay -lLBP and its contact 5S is picked up to interrupt the supply of energy toterrninal l2 of the eld station'unit so that indication codes sent to the oice cause the contacts of relay GLBK to occupy their normal or released position.

As shown, contacts 58 and 59 of relay ALI-ISR are in their left-hand or normal positions and interrupt the circuits for supplying energy to the windings of signals LA and GLB and these signalsare both at stop and establish the circuit of relay 4LRGP so that its contact 55 interrupts the supply of energy to terminal I3. of the field station unit. As section 3T is Vacant, relay ETR is picked up and its contact 6l establishes connection from terminal C of the source to one terminal of the winding of relay STKE, while connection is established from the other terminal of the relay winding to terminal B of the source over front contact 52 of the relay, and also over normal polar contact 63 of starting relay 3-4FST and back contact 64 of the relay MSP of the C. T. C. field station unit. Accordingly, the contacts of relay STKS occupy their normal or picked-up position and its contact 65 interrupts the circuit leading to terminal I0 of the eld station unit, and the indication codes sent to the oflice release relays dLI-IK and 3TK.

Referring to'Fig. 2, which shows the equipment at the oice, the contacts of relay Z-QLP are in their lefthand or normal position in which they designate westbound traflic in the stretch shown in Figs. 1A and 1B. In addition, at this time, relay Z-GLPS is energized by current Ysupplied over its stick circuit and the auxiliary or block indication repeater relay Z-BKSR is released. As relays ITK, STK, ZRBK, LBK, 2RHK and @LI-IK are all released, energy may be supplied to one or the other of the windings of relay 2-4LP on movement of the signal lever ESIG or ASIG to thereby move the contacts of relay z-dLP if the operator wishes to change the designated traffic direction.

For purposes of illustration it will be assumed that the operator wishes to clear the signal LA to authorize a westbound train to enter the stretch. In order vto clear this signal he moves lever QSIG to its left-hand position L and presses the starting button B-ASTB to pick up the starting relay 3-4ST and cause a control code to be sent to field station 3-'-4. On thismovernent of lever llVSIG` the circuit is established to supplyY energy to the lower winding of relay Z-LP but as its contacts are already in their left-hand position the supply' of energy to this winding is without eiect.

During transmission of this control code, relay S-GS picks up so that the code sent to station 3 4 is determined bythe condition of control circuits Y individual to 'this station. This is the casesince 'll of relay 3-!-S, and contact L of leverASIG to terminal 5 of the oftlce coding unit and the control code sent to station 3-5 causes energy to be supplied to relay ALI-ISR to move its contacts 53 and 59 to their right-hand position to establish the circuit controlled by contacts of relay Ll-ID and by switchk controlled contacts andy 9i for supplying energyto signal liLA and this signal is caused to display itsgreen orV clear indication. When the signal LA clears, the crcuit of relay @LRGP is interrupted and `it releases so that its contact 59 establishesthe circuit to supply energy to terminal i3 of the eld station unit. 1n addition, on release of relay LRGP, a contact of the relay momentarily interrupts the circuit of the starting relay S-QFST and reverses its contacts to cause an indication code to be sent to the oilce to pick up relay LI-IK.

At this time contact 63 of relay 3`FST interrupts the pick-up circuit for relay STKS but this relay is energized by currentrsupplied over its stick circuit established by its contact E2 and the relay remains picked up so that its Contact 65 interrupts the supply of energy to terminal Il) of the field station. Y

If a westboundrtrain now enters the stretch, the track relay STR will release when the train enters section 3T. On release of relay SIlr't its contact l2 establishes for relay LBP a stick circuit including reversepolar contact I3 of relay GEFSR so that the contacts of relay dLBP Vremain in their normal or picked-up position after release of neutral contact 54 of relay GLHD as a result of interruption of the circuit of relay LI-ID by contacts '9S and 9'! of relay 3TR.

On release of relay STR. its contact El interrupts the circuit of relay TKS and it releases or is operated to interrupt its own stick circuit while its contact il establishes for relay LBP a stick circuit including reverse polar contact 13 of relay @EFSR so that the contacts o1 relay liLBP remain in their picked up or normal position as long as relay STKS is released.

Gn release oi relay lLHD lthe signal ilLAis put to stop and th-e circuit of relay @LRGP is established so that its contact 65 interrupts the supply of energy to terminal i3 of the field station.

Y After release of relays STR and STKS energy is supplied over back Contact 6 iY of relay 3TR and back contact 'i8 of relay 3TKS to the lower winding of relay liLl-SR to move the relay contacts to their normal positions and prevent clearing of signal LA unless another control code is Sent to this station. Y

As a result of the changes starting .relay -QFST is reversed and an indication code is sent to the ofce to pick up relaySTK, release relay GLI-IK, and to keep relay IELBK in its normal or released position since relay LBPxis energized by current supplied over its stickcircuit. When relay STK picks up, its contact 98 interrupts the circuits of relay -LP to prevent movement of its contacts and thus insure that westbound trac is maintained in the stretch.Y

In addition, when relay `STK picks up,` its contact that the block is occupied,'while .another contact o1 relay STK establishes a circuit for lamp vTKE f attnis station theV and it is lighted to show that section 3T is occupied.

At the end of the indication code sent from eld station 3-4 the relay MSP is released and the contact 63 of relay 3.--4FST is restored to its normal position.

When the train advances into section 8T, the track relay STR releases and interrupts the line Wires 48 and 49 so relay 4LHD remains released, While these wires are also interrupted when the train enters section 1T and relay 'ITR releases.

When the train Vacates section 3T, the relay 3TR picks up and energy is supplied to relay 3I'KS over its pick-up circuit which includes front contact 6I of relay STR, normal polar contact 63 of relay 3-4FST, and back contact 64 of relay MSP, assuming that the indication code is sent to the oflice before section 3T is vacated. Accordingly, relay BTKS picks up or is restored from its released or operated position to its normal position and its contact 62 establishes the relay stick circuit to keep the relay contacts picked up during subsequent reversal of the contacts of relay S-AFST.

When relays STR and 3TKS pick up, their contacts l2 and I'I interrupt the stick circuit for relay ALBP and its contacts release or move to their operated position as the relay pick-up circuit is opened by neutral contact 55 of relay LHD.

`When relay TKS picks up, the contact of this relay in the circuit of relay 3-FST momentarily interrupts the circuit of this relay and its contacts reverse to cause an indication code to be sent to the oilice. As the contacts of relay STKS are in their picked up or normal position, contact 65 interrupts the supply of energy to terminal I E! of the eld station unit, and, as relay ILBP is released, its contact 55 establishes the circuit to terminal I2 of the eld station unit, and the indication code sent to the oiiice releases the relay 3TK and picks up or operates relay LBK On release of relay STK its contact 89 interrupts one circuit for lighting lamp Z-tBm, but at this time energy is supplied to this lamp over front contact `SI of relay 4LBK and back contact 82 of relay 2--4BKSR and this lamp remains lighted to indicate that the stretch is occupied. In addition, as relay STK is released the lamp STKE is extinguished and Contact 93 in the circuits of relay 2--4LP is closed, but at this time contact 99 of relay ALBK interrupts the circuits of relay 2-4LP and therefore insures that the contacts of relay 2-4LP will remain in their left-hand position and maintain west-bound traflic in the stretch.

When the train advances into section 6T, the track relay GTR releases and interrupts the circuit of signal 6L and this signal displays its red or stop indication While the circuit of relay BLPC is interrupted and it releases. In addition, on release of relay ETR energy is supplied to relay BLSR over its pick-up circuit prior to release of relay LPC and relay @LSR picks up to establish a stick circuit to maintain it energized as long as relay SLPC is released, While relay BLSR establishes a circuit to supply energy oi reverse polarity to line Wires 48 and 49. IVhen the train vacates sections 8T and 1T, the energy supplied to line Wires 48 and A3 feeds to relay LLI-ID and picks up its neutral contacts and operates the relay polar contacts to their right-hand positions. Accordingly, contact 53 of relay @LI-ID interrupts the circuit of relay LBP and it remains released or operated and maintains the supply of energy 10 to terminal l2. of the eld station unit so that indication codes sent to the ofce show that the block is occupied.

When the train advances into section 4T, the signal 5L is put to stop an-d relay ELSR is picked up While relay 5LPC is released. Accordingly, energy of reverse polarity is supplied to line Wires 40 and lil, but the circuit of these Wires is interrupted as long as section 5T is occupied and relay rTR is released. In addition, when relay 4TR releases and interrupts the circuit of line Wires 23 and 24, the relay ZRAR releases and its contact 33 interrupts the circuit of relay ZRBP so that its contacts move to their released or operated position in which conta-ct 34 establishes the circuit to supply energy to terminal It of the eld station unit. Also, on release of relay ZRBP, a contact of the relay momentarily interrupts the circuit of relay I-ZFST and its contacts reverse to cause an indication code to be sent tothe oiiice to pick up or operate relay ZRBK so that its contact 84 establishes a circuit to maintain lamp 2-4BKE lighted after release of contact 8l of relay 4LBK. When relay ZRBK picks up or is operated, its contact 85 interrupts the circuits of 'relay 2-4LP to prevent energization of this relay after release ci contact 99 of relay 4LBK.

When the train vacates section 5T and relay ETR picks up, the energy of reverseV polarity supplied to line Wires 40 and 4I feeds to the Winding of signal 6L to cause it to Ydisplay its yellow or caution indication when lighted, While the contacts controlled by the signal mechanism establish the circuit of relay BLPC and it picks up to release relay BLSB. and to. supply energy of normal polarity to line Wires 48 and '49. This energy keeps the neutral contacts of relay 4LI-1'D picked up and moves the relay polar contacts to their left-hand or normal position in which contact 53 establishes the circuit of relay 4LBP andits contacts move to their picked-up or normal position in whichcontact 5S interrupts the supply of energy to terminal I2 of the eld station unit. In addition, a contact of vrelay 4LBP momentarily interruptsthe circuit of relay 3-4FST and its contacts reverse to cause an indication code to be sent to the oflice to release or restore to nor-V mal the contacts of relay IILBK, but the lamp 2-4BKE continues to be lighted by energy supplied over contact 84 of relay ZRBK While the circuits of relay 2--4LP are interrupted by contact 85 ofrelay ZRBK.

Movement of the Westbound train out of the stretch is governed by signal 2L which may be controlled from the cnice by the operator in any suitable manner. The details of the control of this signal are not essential to an understanding of this invention and are being omitted to simplify this disclosure.

If signal 2L is cleared, the train may advance into section IT thereby releasing the track relay I TR so that its contact 36 interrupts the circuit of relay I'IKS and its contacts move to their released or operated position in which contact 38 establishes the circuit for supplying energy to terminal I0 of the eld station unit While the contacts of relay I-ZFST are reversed to cause an indication code to be sent to the ofce to pick up relay ITK and to keep relay 2RBK picked up or operated.

When the train vacates the stretch, the relay ITR picks up and completes the circuit of the line Wires so that relay ZRAR picks up, While the mechanism of signal 5L establishes'the circuit of relay 5LPC and it picks up to release relay ELSR and to cause energy of normal polarity to be supplied to line wires 40 and 4I. Inaddition, when relay I TR picks up, its contact 36 establishes the circuit of relay ITKS and its contacts move to their normal or picked-up position to establish the relay stick circuit, while kits contact 38 interrupts the supply of energy to terminal I of the field station unit.

When relay ZRAR picks up, its contact 33 establishes the circuit of relay ZRBP and its contacts move to their lnormal or picked-up position to interrupt the supply of energy to terminal I4 of the rleld station unit, while at this time the circuit of relay I-ZFST is momentarily interrupted and its contacts are reversed to cause an indication code to be sent to the oice to release relays ZRBK and ITK, thereby extinguishing the lamps ITKE and 2-4BKE and establishing the circuits or relays 2*-4LP.

Y It the operator wishes to prepare the track l stretch for eastbound trafc, he may do so by moving lever 4SIG to its center or its right-hand position and moving lever ZSIG! to its right-hand position, thereby establishing the circuit of the upper winding of relay 2-4LP and moving its contacts to their right-hand or reverse positions.

On `this movement of the contacts of relay 2-4LP,

the polarity of the energy supplied to relay 2-4LPS is 'changedand itV releases to interrupt its own stickvcircuit `and to establish circuits for relays Ziel-3K,V 4LBK and 2-4BKSR which pick upor are operated and establish stick circuits for themselves. At-this time contact 88 of the auxiliary or block indication repeater relay @-IBKSR shunts the contacts 85 and 99' of relays 2RBK andLBK in the circuitsof relay 2J- 4LP and permits operation of relay 2-4LP to change the designated traiic direction veven though relays ZRBK and BLBK are operated or picked up.

If either starting buttonI-ZSTBor 3--4STB isnow pressed, the starting relays I-2ST and 3--4ST are both picked. up to initiate transmis sionof control codes to the field stations at both ends of the stretch, While at this time energy is supplied to relay 2-,4LPS over its pick-up circuit and its contacts pick up to estabish the relay stick circuit..` The energy which is `supplied to the pick-.up circuit for relay 2-4LPS is .supplied from terminal 51 or the office coding unit. As explained in application Serial No. 496,907 of A. P. Jackel, energy is supplied to this terminal when and only when the oiiice coding unit is condi-` tioned to transmit a code. As long as relay 2-4LPS is released it establishes circuits for relays ZRBK and 4LBK, and this arrangement for] delaying energization of relay 2-4LPS until the; oice coding .unit is in condition to transmit pre-` vents premature release of relayZRBK or .4LBK

by an indication code received after reversal of` relay`2-4LP-to change the designated traic di-` rection, but prior to transmission of control codes to causeA the wayside equipment to prepare the stretch for traffic inY the'new direction. When relay 2'-4LPSpi-cks up, it interrupts the pick-up circuit for the `auxiliary or block indication repeater relay 2-4BKSR, but it remains picked up-l until relays 2RBK and 4LBK are both released` orrestored'to4 normal, while after picking up of relay 2-4LPS the relays ZRBK and4LBK remain operated or picked up until suitable indication` codes are received from the eld stations.

Thecontrol code sent to field station I-2 at this time-reversesthe contacts of relay ZWFSR,

and the control code' sent to -field station 3 4.`

moves the contacts of relay IIEFSR to their nor'- l2 mal position. In addition, during transmission of the control code to station I-2 the starting relay i-ZST at the oiiice is released, While the starting relay 3-4ST is released during trans- `mission of the control code to station 3 4.

When relay ZWFSR reverses, its contacts 26 and 2| interrupt the supply of energy to line Wires 23 and 24 and connect these Wires to relay ZRHD. At this time relay ZRAR releases and its contact 33 interrupts the circuit of Vrelay ZRBP and its contacts move to their released or operated posivtion to cause an indication code to be sent to the oiiice which maintains relay ZRBK operated or picked up. When the supply of energy to Wires 23 and 24 is cut off the winding of signal 5L is deenergized and the contacts operated by the signal interrupt the circuit of relay SLPC and'it releases to interrupt the supply of energy to line Wires 49 and 4l so that signal 6L is deenergized and interrupts the circuit of relay BLPC. Accordingly', relay SLPC releases and interrupts the supply of energy to Wires 48 and 49 and connects these wires to the winding of signal 6R,

When the contacts of relay IIEFSR are moved I to their normal position, the relay 4LHD isV deenergized and its neutral contact 54 interrupts the circuit of relay 4LBP. After reversal of the contacts' of relay 4EFSR, energy is supplied to line Wires 48 and 49 through the Winding of relay 4LAR. and relay 4LAR picks up and its contact 89 establishes a circuit for relay 4LBP and it picks up so that indication codes sent from eld station 3-4 to the -oiiice release or restore to normal the contacts of relay 4LBK, but at this time relay 2-4BKSR is maintained energized by current supplied over the stick circuit established by contact Sie of relay ZRBK.

The current supplied through the Winding of n relay 4LAR to line Wires 48 and 49 is of one polarity or the other depending on the position o pole changing contacts Which may be governed in any suitable manner. The energy supplied to line wires 48 and 49 energizes the Winding of signal SR. so the contacts of the signal establish the 45V circuit of relay @RPC and it picks up to cause energy of normal polarity to be supplied to line Wires 40 and 4I. The current supplied to these Wires energizes signal 5R so it establishes the circuit of relay SRPC and it picks up to cause current of normal polarity to be supplied to wires 23 and 24. This energy picks up the neutral contacts of relay ZRHD and moves the relay contacts to their normal position. If the control code sent to station I-2 reversed the contacts of relay ZRHSR, one or the other of the signals lRA or 2R13 Will be cleared to authorize an eastbound train to enter the stretch.

When energy of normal polarity is supplied to relay ZRHD, its polar contact and its neutral contact 9! establish the circuit of relay 2RBP and its contacts move to their normal or picked-up position to interrupt the circuit leading to terminal I4 of the eld station unit so that indication codes sent to the oce release or restore to normal the contacts of relay ZRBK, thereby in-` tablishes the circuit of the lamp 24BKE.

If one of the signals ZRA or ZRB had cleared 13 before the indication code was sent to the oiice, the relay ZRRGP at the eld station would have been released and the indication sent to the oice Will pick up relay ZRHK so that its Contact 3 interrupts the circuits of relay 2-4LP.

Because of use of the C. T. C. line wires for transmission of control codes, or for the transmission of indication codes from other eld stations, the field station I-2 may not be able to transmit an indicati-on code to the oiiice for a substantial time interval subsequent to establishment of eastbound traffic in the stretch and resultant picking up of relay ZRBP, and also of clearing of one of the signals ZRA or ZRB. A train may enter the stretch immediately after clearing of one of the signals 2RA or 2RB and when the train advances into section IT, it releases track relay I TR so that its contacts interrupt the line Wires 23 and 24 to deenergize the relay ERI-ID, While contact 36 of relay ITR interrupts the circuit of relay ITKS and it releases or is operated With the result that energy is supplied to the lower winding lof relay ZRI-ISR over back contact 94 of relay ITKS and back contact 36 of relay ITR. The energy supplied to relay ERHSR over this circuit restores the relay contacts to their normal position so the signals ZRA or ZRB are held at stop.

If on release f the relay ZRHD and consequent interruption by its neutral contact 9! of the circuit of the relay ZRBP, the contacts of relay ZRBP should move to their operated or released position, its contact 34 would establish the circuit for supplying energy to terminal i4 of the eld station unit se that indication codes thereafter sent to the o-iiice would keep the relay ZRBK operated or picked up, and its contact 95 would maintain the stick circuit of relay 2-4BKSR. Under these conditions, therefore, relay 2-4BKSR would remain energized and its contact 88 would maintain the circuit shunting contacts 85 and 99 of relays ZRKB and 4LBK inthe circuits of relay 2--4LP, and the operator would be free to energize the relay 2-4LP to move its contacts and change the designated traffic direction even though the stretch is occupied. If the contacts of relay 24LP should be moved and a control code should be sent to station 3 4, relay liLF-SR would be reversed and the supply of energy to line wires 48 and 49 Would be cut off with resultant deenergization of the other line circuits and display of sto-p indications by signals 5R and 5R. The presence of the train in the-stretch would prevent clearing of the signals governing movement of Westbound traic in the stretch but the interference With the signals governing eastbound traic is objectionable and would delay trailic, and this system is arranged to eliminate the possibility of the diiiiculty just described.

Referring to Fig. 1A, it will be seen that on release of relay ITR its contact |00 establishes for relay ZRBP the stick circuit including its own front contact lill and reverse polar contact 32 of relay ZWFSR, While on movement of the contacts of relay ITKS to their released or operated position contact |02 establishes another stick circuit for relay ZRBP. Accordingly, on entrance of a train into the stretch, the contacts of relay 2RBP remain in their normal or'picked-up position after release of relay ZRH'D so contact 34 of relay ZRBP continues to interrupt the circuit leading to terminal I4 of the eld station unit.

The pick-up circuit for relay ITKS is controlled by contacts of relays I-2FST and MSP so that the contacts of relay ITKS are certain to remain in their released or operated position until an indication code is sent to the oice, and as relay I TKS when released establishes a stick circuit for relay 2RBP, the contacts of relay ERBP are certain to remain in their picked up or normal position until an indication code is sent to the office.

When an indication code is sent to the ofl'lce with relay ITKS operated or released and the contacts of relay rRBP in their normal or picked up position, the relay ITK is picked up and the relay ZRBK is released so that its contact 95 interrupts the stick circuit for relay 2-4BKSR and it releases with the result that its contact 88 interrupts the circuit shunting contacts and 99 ci relays ZRBK and 4LCBK in the circuits of relay Emili?. At this time contacts 85 and 99 are released, but the circuits oi relay 2-4LP are interrupted by contact @i of relay ITK so the contacts ci relay 2-4LP cannot be moved.

In addition, en release of relay Z-IIBKSR, its contact 32 establishes the circuits governed by relays ERBK and ILBK for lighting lamp 2 4BKE but at this time this lamp is lighted by current supplied over front contact 86 of relay ITK.

When the train vacates section IT, the relay ETR picks up and its contact 36 establishes the pick-up circuit for relay ITKS,'assuming that an indication code hasfbeen sent to the office so that this circuit is established by relays I-ZFST and MSP. When relays ITK and ITKS are both picked up, the stick circuits for relay ZRBP are interrupted and its contacts move to their normal or released position to establish the circuit for supplying energy to terminal I4 of the ield station unit. The indication code now sent to the office releases relay ITK and picks up or operates relay 2RBK so that lamp 2-4BKE is lighted by energy supplied over back contact 82 oi relay --LIBKSR and front contact 34 of relay 6RBK In addition, on picking up of relay ZRBK, its contact 35 interrupts the circuits oi relay 2-4LP to prevent movement of the contacts or" this relay after closing of contact 8l of relay ITK. The contact 85 of relay ZRBK is certain to be effective to prevent energization of relay mLP at this time, since, as explained above, the relay 2-4BKSR is certain to be released so that its contact B8 interrupts the circuit shunting contact 85 of relay ZRBK.

The C. T. C. field station units are arranged so that, after a station has transmitted an indication code, it cannot thereafter transmit another indication code if another station has an indication stored for transmission. Accordingly, if, at the time a train enters the stretch and station I-2 sends an indication code to the oiiice which releases relay ZRBK, an indication code has not been sent from station 3-4 to release relay QLBK, the indication code sent from station I-Z to pick up relay ZRBK will not be transmitted until after the indication code has been sent from station 3-4 to release relay 4LBK. As a result, relays ZRBK and 4LBK are certain to both be released for at least a short time interval, so the stick circuit for relay 2-4BKSR is interrupted to insure release of relay 2-4BKSR.

It will be seen, therefore, that during occupancy of the stretch the circuits of relay 2-4LP are interrupted by contact 81 of relay ITK or by contact B5 of relay ZRBK so there is no possibility that the contacts of relay 2-4LP can be moved during occupancy of the stretch. Ac-

cordingly,the established traic direction will be maintained during occupancy of the stretch.

As the relay 2-4BKSR is certain to be re-` occupancy of the stretch. This elimination of` undesired lighting of lamp Z-llBKE when relay ERBK or 'SLBK is picked up because of a change in the direction of tralic in a stretch makes this lamp more effective to show occupancy of the stretch and simplifies the Work of the C. T. C. machine operator.

On continued movement of the eastbound train through the stretch the equipment operates in the usual manner, and a detailed explanation of the operation of the equipment at such times is unnecessary, except to point out that, when the eastbound train advances beyond signal 6R, the circuit of line wires 48 and 49 is interrupted and relay /iLAR releases so that its contact 89 interrupts the circuit of relay QLBP and it is operated or releases to cause a block occupied indication code to be sent to the ofiice. When the eastbount train enters section 3T, the relays STR and STES release but the stick circuit for relay @LBP is not established as this circuit is interrupted by a Contact of relay liLBP, and also by contact 'i3 of relay SEFSR which occupies its normal position at this time.

Although the invention has been illustrated and described in connection with a stretch of track equipped with Wayside apparatus which is arranged so that trafic conditions in a portion of the stretch are indicated from one end of the stretch and traffic conditions in the remainder of the stretch are indicated from the other end of the stretch, it should be understood .that the invention is not limited to this arrangement but is applicable also to stretches in which trafc Y conditions throughout a stretch are indicated from one end or the other of the stretch.

Similarly, although the invention has been illustrated and described in connection with a stretch' of track equipped with Wayside signaling apparatus governed over line Wires, t'he invention is also applicable to stretches equipped with other forms of Wayside signaling apparatus, such, for example, as coded track circuit signaling equipment.

Although we have illustrated and described one form of railway signaling apparatus embodying our invention, it should be understood that variousl changes and modifications may be made thereinwithin the scope of the appended claims Without departing from the spirit and scope of our invention.

Having thus described our invention, what We claim is:

l. In a system of centralized traffic control for a stretch of single track railroad between the ends of adjacent passing sidings and equipped with a code typeV communication system connecting the ends of said stretch with a control ofce, said code communication system including at each end of the stretch a starting relay having contacts which are moved lfrom a normal to an operated position in response to a ch'ange in aptoV paratus conditions at that location` and are re-` stored'to theirinormal position in response to transmission of an indication code from that location to the ofce, in combination, a block relay at each end of the stretch controlling transmission of indication codes to the office to show trafiic conditions in the stretch, a system of reversible circuits extending the length of said track stretch and governed by traic conditions in the stretch, said system of circuits being manually controlled from said oiice through' said code communication system so as to at times prepare the stretch for trahie in one direction and to at'other times prepare the stretch for traffic in the other direction, said system of circuits being operative when conditioned to prepare the stretch for traffic in either direction to control the signal and a block indicationl control circuit at the corre.- sponding entrance end of the stretch in accordF ance with tramo conditions in at least a portion ci said stretch, a detector track section at each end of the stretch including the-track switch for connecting the track stretch with the adjacent passing siding, each detector track section being provided with a track circuit including a track rela f, each detector section track relay having associated therewith a detector section repeater relay, means for each detector section repeater relay for causing its contacts to move from a normal to an operated position when the associated track relay releases, means for each detector section-repeater relay for causing its contacts to move from their operated to their normal position when and only when the associated track relay is picked up and the contacts of th'e associated starting relay are in their normal position, means for each or" said block relays for moving its contacts from an operated to a normal position when the associated block indication control circuit shows that the track stretch over which it is controlled is unoccupied, means effective on movement of the contactsofV a detector section repeater relay to their operated position when the contacts of the associated block relay are in their normal position to maintain the contacts of said block relay in their normal position as long as the detector section repeater relay contacts are in their operated position, each detector section repeater relay governing a detector Section indcation relay at the ofiice through said code corn-k munication system and each block relay governing a block indication relay at the-office through said code communication system, and means at said oilice governed by the detector section and block indication relays associated with said trackv stretch for governingtransmission of control codes by said code communication system to cause said system: of reversible circuits to maintain the established directionof traffic during occupancy of said stretch.

2. In a system ci centralized trafc control for a stretch ci single track railroad between the ends of adjacent passing sidings and `equipped with a code type communication system connecting the ends of said stretch With a control oce, said code communication system including at each end yof the stretch a starting relay having contacts .which are moved from a normal to an operated position in response to a change in apparatus conditions at that location and are restored to their normal position in response to transmission of an indication code from that location to the ofce, in combination, a block relay at each end of the stretch controlling transmission of indication codes to the office to show traffic conditions in the stretch,

a4 system of reversible circuits extending the length of said track stretch and governed by trafc conditions inthe stretch, said system of circuits oeing manually controlled from said oflice through said code communication system so as to at times prepare the stretch for traic in one direction and to at other times prepare the stretch for traiic in the other direction, said system of circuits being operative when conditioned to prepare the stretch for trailc in either direction to control the signal and a block indication control circuit at the corresponding entrance end of. the stretch in accordance with traffic conditions in at least a portion of said stretch, a detector track section at each end of the stretch including the track switch for connecting the trackstretch with the adjacent passing siding, each detector track section being provided with a track circuit inlcluding a track relay, each detector section track relay having associated therewith a detector section repeater relay,v meansv for each detector section repeater relay for causing. its contacts to move from a normal to an operated position when the associated track relay releases, means for each detector section repeater relay for causing its contacts to move from their operated to their normal position when and only when the associatedtrack relay is picked up andy the contacts of the associated starting relay are in their normal position, means for each of said block relays for moving its contacts from an operated to a normal position when. the associated block indication control circuit shows that` the track stretch over which it is controlled is unoccupied, means effective on movement of the contacts of a detector section repeater relay to their operated positionwhen the contacts ot the associated block relay are in their normal positionto maintain the contacts ot said; block relay in their normal position as long as the detector section repeater relay contacts are in their operated position, each detector section repeater relay governing a detector section indication relay at the office through said code communication system and each block relay governing a block indication relay at the.` oiiice through said code communica.- tion system, a block repeater relay at thev oflice, means for moving the. contacts of said block repeater relay from a normal to an operated position when the designated direction of trahie in said stretch is changed, means for moving the contacts of said block repeater relay to their normal position when said block indication relays are positioned by indication codes' which show that the stretch is unoccupied', and means at said oflice governed by the detector section. and block indicationy relays and by the block repeater relay associated with said track stretch for governing transmission oi control codes by said code communication system to cause` said system of. reversibie lcircuits to maintain the established. direction of tramo during occupancy of said stretch.

3.. In a system of centralized trailic. controla tor a, stretch of single track railroad between the ends of adjacent passing sidings and equipped with a code type communication system connecting the ends or said stretch with a control einem. said code coinrnunicationl system including at each i end of the stretch` a starting relay having contacts which are moved from a normal toan operated position in response toa change irc apparatus conditions at that location and are restored to theirv normal positiony in respon-se totransmission of an indi-cation code from that location to the oilice, in. combination, a block relay at each end 1'8A of the stretch controlling transmission of indication codes to the oice to show traffic conditions in the stretch, a system of reversible circuits extending the length of said track stretch and governed by traic conditions in the stretch, said system of circuits being manually controlled from said office through said code communication sys tem so as to at times prepare the stretch for traffic in one direction and toV at other times prepare the stretchy for trailic in the other direction, said system of circuits being operative when conditioned toA prepare the stretch for traffic ineither direction to control the signal anda block indication controly circuit. at the corresponding entrance end of the stretch in accordance with traific conditions in at least a portion of said stretch, a detector track section at each end of the stretch including the track switch for connecting the track. stretch withI the adjacent passing siding, each detector track section being provided with a track circuit including a track relay, each detector section track relay having'associated there.- with. a detector section repeater relay, means for each detector section repeater relay for causing its contacts. to move from a. normal to an. operated position. when. the associated track. relay releases, means for eachA detector sectionV repeater relay for causing its contacts to move from their operated to their normal position when andl only when the associated track relay is picked up and the contacts. of. the associated starting. relay are in their normal position, means for each of said block relays. for moving its contacts from an operated to a normal position when the associated block indication control circuit shows that the track stretch over which it iscontrolled is unoccupied, means effective on movement of the. con.- tacts of a. detector section repeater relay to their operated position when the contacts of the associated block relay are in their normal position to maintain the contacts of said block relay in their normal. position as long as the detector section repeater relay contacts are in their operated position, eachdetect'or section repeater relay and each block relay acting through said code communication system according as its contacts oc.- cupy their normal or their operated position, to cause the contacts of. a. detector section or ablock indication relay at the office to occupy their normal or their operated positions, a block repeater relay at the oiiice, means for movi-ng the contacts of said block repeater relay from their normal to their operated position when the designated direction of trailic in said stretch is changed, means for movi-ng the contacts ot said block` repeater relay tok their normal position when said block indication relays are positioned by indication codes which show that the stretch. is unoccupied, and means at said oice effective to main.- tain the established direction of trafficin said stretch when the. contacts of the block indication relay controlled by the: block relay at the: designated entrance end of the,l stretchoccupy their operated` position provided the contacts. of. saidblockrepeater relay occupy theirV normal position or when the contacts of the indication relay for the detector section at the entrance end Vof the stretch occupy their operated position.

4. In a system of centralized traffic control for a stretch of single track railroad connected at the ends yby track switches with adjacent passing sidings and equipped with a, cod-e type communication system connecting the ends of said stretch with a control oliicc, said codeV communication system including at eachv end of the stretch a l9- f starting relay having contacts which are moved froma normal to an operated position in re-i sponse to a Vchange in apparatus conditions at that location and are restored to their normal position in response to transmission of an indication code from that location to the oice, Vin combination, a detector track section at each end of `the stretch including the associated track switch and provided with a track circuit includ--` ing Va track relay, a system of reversible circuits extending the length of said stretch and governed by traffic Vvconditions inthe stretch, said system of circuits being adapted to at times prepare the stretch for traffic in one direction and to 'at other timesprepare the stretch for traflic in the other direction, said system of circuits being operative whenconditioned to Ypreparejthe stretch for traiicin either direction to control the signal and a-,block indication control circuit atthe corresponding entrance end of the stretch in accordance `with traic conditions in at least a portion of said stretch, manually controlled electroresponsive means at said office for designating the direction of trafc movements in said stretch and controlling the transmission of control codes by said code communicationsystem by which said system of reversible circuits is conditioned to prepare the stretch for traffic in one direction Yor the other, each detector section track relay having associated therewith a detector section remv peaterrrelay, means for each detector section repeater relay for causing its contacts to move from anormal to an operated position when the associated track relay releases, means for each de"-V tectorjsection repeater relay for causing its con'- tactsY to move from their operated to their nor'- m'al'position when and only When the associated track relay is picked up and the contacts of the associatedstarting relay are in their normal po-V sition,'a block relay at each end of the stretch,

means for `each ofsaid :block relays for moving Y its contacts from an operated to` a normal positionv when theassociated block indication control circuit shows that the track stretch Yover which itisY controlled is unoccupied, means effective when the contacts ofrardetector sectionV repeater i relaygare moved to their operatedposition and thejcontacts of the associatedblock relay are'in ol?v said `block relayrin their-normal position as Y long as'the contacts oisaiddetector section re` controllingthe electro-responsive means for saidstretch to maintain the established direction of trame during occupancy of the stretch.V

Vtheir Ynormal position to Vmaintain. the contacts 5o Y 5; In' a system of centralized traiic control for aZ stretchofsingle track railroad connected at the ends by track switches with adjacent passing sidings and equipped with a code typecorninunb cation system connecting tlieends of said stretchV Vvwith va controlV oice, said lcode communication system including at each endl Vof the stretch a starting relayV having contacts which are moved from a. normalto anV operated position in response to'a change in apparatus conditions at'that loca-k tion' fand are restored to their;Y normal vpositionV in response to transmission ofV an indicationfcode from 4that location Vto the cnice, in combination,

a detector track section atfeach end ofthe stretch conditioned to prepare the stretch for traflic in either direction to control they signal and a block Y indication control circuit at the corresponding entrance end of the stretch in accordance with trailc conditions in at least a portion of said stretch, manually controlled electroresponsive means at said office -for designating the direction of traffic movementsin said stretch and Ycontrolling the"transmission of vcontrol codesrbyA said code communication system by which said system of reversible circuits isY conditioned to prepare Y the stretch for traiilc in one direction or the other,

each` detector section track relay having associated therewith a repeater relay, meansfor each detector section repeater relay for causing .its

, contacts to move from a normal to an operated position when the associated track relay releases, means for each detector section' repeater'relay for causing its Acontacts to move from theirk operated to their normal positionY when and only when the associated track relay is picked up and the contacts ofY the associatedstarting relay are in their normal position,A a`blockk relay at each end of the stretch, means foreach of said block relays for moving its contacts from an operated to a normal position when the associated :block indication control circuit shows that thertrack stretch overwhich it is controlled is unoccupied,

means effective when the contacts oa detector section repeater relayare moved to their operated position and the contacts of the associated block relay are inv their normal position to maintain the contacts of said block relay'inV their normal position as long as the contacts of said detector ofce governed through said code communication system in accordance with the position of the contacts of said detector 'section'repeater relays, Y

block indication relays at said oice governed through said code communication system in `accordance with the position of the contacts vof said Y block relays, and'mea'ns includingsaid detector section and .block indication relays for controlling said electroresponsive meansY to cause it toi maintain the .established direction of trac in Y said stretch during occupancy thereof.V i

6. In a system of centralized traffic control'for a stretch ofY track through which traflic may move in a given direction and equipped with a code type communication system connectingfthe ends ofrsaid stretch withy a control oice, said 5 code communication system includingat the en'- trance end of the'stretch a starting relay having contacts which aremoved 'from a normal to an operated position in response to a Vchange inapparatusY conditions at saidalocation and are"Y restored. to their normal position in response to transmission of an indicationV codefrom that location'to'v the oiiice, in combination, a detector track section at .the entrance end of said track stretch, l saidv detector track section having a track Ycircuit'includinga track''relay, a system communication system to at times. prepare said stretch for traffic in said given direction, a signal atfthe entrance end? of said stretch governed by. said system of circuits, a block relay at the entrance end' of said stretch, means governed by saidsystem of circuits for moving the block relay contacts fromV their operated to their normal position whenI said system of circuits prepares said stretch for traino and for thereafter maintaining said relay contacts their operated position provided said stretch i'sfvacant, adetector' section repeaterrelay, means for saiddetectorfsection-y repeater relay for causing. its -contacts tomove fromy anormal to an operated position when thel associated track` relay releases, means for said detector section repeater relay forI causing its contacts to move from their operated'l to their normal: position when and.` only when the associated track relay is picked up and the: contacts of the associated ,starting rela-y are intheir normal position, means effective when the contacts of said detector section repeater re'l'ay are moved to their operated position and ther contacts. of said block relay occupy their normal position to maintain the contacts. of. said block relay in their normal` position as long as the contacts of said detector section repeater relay-occupy theirA operated position, a detector section indication relay at the oiilce governed through said code communica-tion system in accorda-nce with the.v position of the.- contacts of saidi detector" section repeater relay, a block indication relay at the oice governed throughsaid. code communication system having contacts which are moved to a normal or to an operated position in accordance with the position of the contacts of said vlc'l'oclr relay, a block repeater relay at the cnice having' contacts which occupy anoperatedi position when said stretch is not prepared fory traiiic, means'. for moving the contacts of said block repeater relay to a normal position when said block indication relay responds to an indicationV code transmitted: from the 'entrance end or said stretch while the con;- tactsof said block relay occupy thenl normal position, means eiective: provided the contacts of said block repeater-'relay are in their' normal position for maintaining them in; such position when the. block indication relay responds. toe an indication code transmitted vvhi'le the contacts of said block relay are in their operated position, and means. governed by said. detector. section indication relay and by said't block indica.- tion and block indication repeater relaysiandy operating through said: code communication system for' causing said system of' circuits to. maintain traiicin said stretch.

'7.'In' a` system centralized tralic control. for a stretch of track` through which traic may move in a given direction and' equipped. with a code type communication system connecting the endsk of sad stretchy witlr a control office, said code,` com;- munieation system including at the entrance end of thel stretch a starting relay having contacts which are movedfrom a normal to an. operated position in response to a change in7 apparatus conditions at said location and are restored to their normal position response to transmission of anindication code from that. locationv tothe oillcel in combination; a detector track section at the entra-nce end of' said track stretch, said ndetectortrack hav-inga track circuit including atrack relay, a system ot circuits extendingthe length of said stretch and' govern-edby tra-ine conditions in said' stretch'and controlled from 22,. said oflicethrough. said code communication Sys.- tem to at times prepare said' stretch for traiic in said given direction, a signal at the entrance end of said stretch governed by said system of circuits, a block relay at the entrance end oi said stretch, means governed' by said'. system ot' cir'- cuits for moving the block' relay contacts from their operated to a normal; position when said system of circuits prepares said. stretch for tramo and for thereafter maintaining said relay conltacts in their normali position. provided said stretch is vacant, aV detector: section repeater' relay, means. for said detector section repeater relay for causing its. contacts to. move. from anormal tol an. operated position when the associated trac-k relay releases', means` for said; detector' section repeater relay for causing its contacts to move: from their operated' to their normal position when, and only vvhen the associated trackv relay is. picked up and the contacts of the associated starting relay are in their normal position, means effective when the contacts ofV said* detectorl section repeater relay are moved to their operated position and the contacts of' said block relay occupy theirnormal position to maintain the contacts of said block relay in their normal position. as long as the con.- tacts of said 4detector section repeater relay occupy their operated. position, a blo-ck indication relay at the office governed through said. code communication system and. having. contacts which are moved to a normal or to.: an operated position in accordance. with the position` ot the contacts of said block relay, a block repeater relay at. the oice having contacts` which occupy an operated position when said stretch; is.v not'. pre1- pared for tra'ic, means for movi-ng the contacts of said block repeater relay to a normal position when said block indication relay responds t0.- an indication code transmittedy from the. entrance end. ot said stretch While the contacts oi" said block relay occupy their normal positiom means effective provided the. contacts of said block repeater relay are in their normal position for maintaining them in such position when the block indication relay responds to an indication code transmittedl While. the contacts` of said block relay are in theirl operated position, and.' means operating through said' code communication system vfor causing said system of' circuits to main.- tain trai-lic in said stretch when the contactsv of said block indication repeater relay are. irr their normal' position and thev contacts of sadl block indication relay are: in. thepositorr. which they occupy when the relay respondsv to anE indication code transmitted` from the entrance end or' the stretch. WhileV the contacts of said block relay are in their operated position.

8i. In. a system. of centralized trafc control: for a stretch or track through which trani@ may move in a given direction. and: equippedwitlia. code type communication systemconnecting the ends of said stretch with a control office, said code communication system including at the` entrance end? of thestretch. a` starting7 relay having. contacts which are moved from` a. normali to an. operated position in response to a. change in ap'- paratus conditions. at said locationand'. are re:- storedtov` their normal position in response to transmission ot an indication code. from that. location to the. oiiice', in combination, a. detector track section at. the entrance end-of said track stretchy, saidI detector' track section having a track circuit including a track relay, asystem of circuits extending' the, lengthoiA said stretclfrx and governedby trame conditions in: said stretctr and 23 i controlled from said oice through said code communication system to at `times prepare said stretch for traic in said given direction, a signal at the entrance end of said stretch governed by saidV systemV of circuits, a block relay at `the entrance end of said stretch, means governed by said system of circuits for moving the block relay contacts from their operated to their normal positionV when said system of circuits prepares said stretchsfor traffic and for thereafter maintaining said relay contacts in their normal position provided said stretch is vacant, a detector section repeater relay, means for said detector section repeater relay for causing its contacts to move from a normal to an operated position when the associated track relay releases, means for said detector section repeater relay forV causing its contacts yto move from their operated to their normal 4position when and only when the associated track relay is picked up and the contacts ofthe: associated starting relay are in their normal position, means effective when the contacts of said detector section repeater relay are moved Y to their operated positionV and the contacts of said block relay occupy their normal position to maintain the contacts of said block relay in their l peater relay to a normal position when said block indication relay responds to an indication code transmitted from the entrance end of said stretch while the contacts of said block relay occupy their normal position, means eiective provided the contacts of said block repeater relay are in their normal position for maintaining them .in suchposition when the block indication relay respondsV to 'an indication code transmitted while the contacts of said block relay are in their operated position, and occupancy indicating means at saidiofce governed by said clock indication relay provided the contacts of said block indication re-V peater relay are in their normal position.

9. Ina system of centralized traffic control for a stretchY of track through which trailic may move in a given'direction and equipped with a code type communication system connecting the ends of said stretch With a control oice, said code communication system including at the entrance end of the stretch a starting relay having contacts which are moved from a normal to an operated position in response to a change in apparatus conditions at said location and are restoredto their normal position in response to transmission Vof an Y'indication' code from that location to the office, in combination, 'a detector track section at the entrance end of saidY track circuit includinga track relay, a system of circuits extending the length of said stretch and governed by traic conditions in said stretch and controlled from said oioce throughsaid code communication systemY to at times prepareA saidV 24i said system of circuits for moving the block relay contacts from their Yoperated toVv their Vnormal position WhenY said system of v circuitsIprepa-res said stretch for traii'ic and for thereafter ,maintaining said relay contacts in theirY normal position provided saidi stretch is vacant, a detector section repeater relay, means for said detector; sectionrepeater relay for causing its contacts to move from a normal to an operated position When -the Yassociated track relayv releases, means for saiddetector section repeater relay `forcaus ing its Vcontacts to move fromtheir operated to their normal position when 'and only WhenY the associated track relay is picked up and the contacts of the associated starting relay are ,-in their norma1 position, means effective yWhenithe,con-- tacts of said detector seetionrrepeater relayyare Vmoyed to their operated position and the Ycontacts orsaid block relay occupy theirnormal position4 to maintain the contacts of said fblqck relay in'their norma1 position as long asthe Y contacts of, said detector section repeater relay occupy their operated position, a detectorfsectionV indication; relay at the oce governed through/said code communication system'fin accordance; with the position of the contacts of Vsaid 4detector section repeater relay, a block kindi-` cation relay at Ythe oice governed through said code communication system and having 'contacts Y which are moved to a normal or to anoperated positionV inV accordance with the positionof the Y contacts of said block relay, aV block repeater Y relay at the oice having contacts Which. occupy stretch, said detector track section having a track y track section at the entrance end of said track ,c stretch, said detectontrack section having Va Y V an operated positionwhen said stretch islnot prepared for traffic, means lfor movingthe contacts'of'said block repeater relay toa vnorma1v position when said block V`indication `relay 1je'- sponds to an indication code transmitted from the'` entrance yend of said Vstretch lWhile the contacts of said blockV relay occupytheirA normal position, means effectverprovided the. contacts of :said block repeaterrrelay are in their norma1 position for maintaining them :in such v,position Whenfthe block indication relay vrespondsjo VAan indication codeV transmitted fvvhile thev contacts ofsaidblock relay are in theirv operatedpositionfoccupancy indicating; means yat said oice,

means governed by said-detector section indica- A tion relay for controlling saidoccupancy indicate ingY means, and means governed Aby said .block indication relayA provided ther/,contactsV otaid blockzindication repeater relay arelin their nor.

mal Yposition for also controlling said occupancy indicating'meansf l '10."In' asy'stem off code type Vcommunication system connecting Athe ends of saidfstretch With a control ofce, said code communication'system including at the eneY transmission of an indication code from thatY location tothe oiice, incombination, a detector.

track circuit includinga track relay, yaM system of circuits extending the length of said'st'retch o' y and governed by traic conditions-,in said stretch andr controlled vfrom saidL oice tliiflghsaid code communicationsystem to at times'prepare Vsaid stretch `for traiiic insaid given direction, a; signal *c'entraiizedQtaflicAV control for a stretch of trackthrough Which-trailicimay f move in a given direction andgequippedfwitha Lenaerts? 25 at the entrance 'end `.'orrsafid .stretch :governed by .swim-system of circuits, a lbloek relay :at the entrance fend of .said stretch, mea-ns :governed `by said .systeinof circuits for moving 'the block relay --ccntacts Vfrom their operated te their :normal position when said system of circuitseppares `said stretch zfor tr'a'flic and .for thereafter-Smaltitaining said relay contacts their lnormal position :provided .said stretch vacant, .a detector section .repeater relay, imeans for .said detector section repeater :relay 'for :causing .its .contacts to .move 'from a normal 'to :an Loperated position when the :associated .track relay releases, means for said 4detector'section repeater relay vfor causing its contacts to move from their operated to their normal position 'when and .only when the associated track zre'lay is picked up and fthe contacts of the associated starting V'relay fare in their normal position, :an .auxiliary .relay at said omce having contacts which occupy .a .normal position when .said .stretch `not prepared for traine, .means governed through :said code communication system by :sai-d .detector section repeater :relay and `by said .block relay .in response 'to :operation of said 'system of circuits to prepare 1 sain stretch for traino 'in said given direction for 'moving the contacts .of said auxiliary lrelay to their operated 'position :and 4.for thereafter .maintaining them in Asuch position Iduring occupancy of the stretch, and occupancy Bindi-- cation :means at said cnice governed by said block relay through said code communication system provided the contacts of said auxiliary relay are in their operated position.

Y11.-In a `system of centralized traffic control for a stretch of track through which traflic may move in a given direction and equipped with a code type communication system connecting the ends of said stretch with a control office, saidcode communication system including .at the entrance 'end of the 'stretch a starting relay having contacts which Aare .moved from a normal to an voperated position in response to a change in apparatus conditions at said location and are restored to their normal position in response to transmission of an indication code from that location to the oliice, in combination, a detector track section at the entrance end of said track stretch, said detector track section having a track circuit including a track relay, a system of circuits extending the length of said stretch and governed by traflic conditions in said stretch and controlled from said oce through said code communication system to at times prepare said stretch for traflic in said given direction, a signal at the entrance end of said stretch governed by said system oi circuits, a block relay at the entrance end of said stretch, means governed by said system of circuits for moving the block relay contacts from their operated to their normal position when said system of circuits prepares said stretch for trac and for thereafter maintaining said relay contacts in their normal position provided said stretch is vacant, a detector section repeater relay, means for said detector section repeater relay for causing its contacts to move from a normal to an operated position when the associated track relay releases, means for said detector section repeater relay for causing its contacts to move from their operated to their normal position When and only when the associated track relay is picked up and the contacts of the associated starting relay are in their normal position, a block indication relay at said oflice governed by said block relay through said code communication system,

26 a block .indication repeater .relay a't Vsaid 'pince having :contacts lwhich voccupy fan operated .position when saitlfstretch i's not prepared for Ltric, means governed through' said c'ode communicationfsystem by said 'detector section 1repeaterrelay `and by ysaid block :relay in response to "operation vof `said 'system 7of circuit-s. to .prepare said s'ti'et'c'h .for traffic in 'said Y.gl-ven direction or 'moving `the contacts of sai-d block :indication repeater relay to their-normal position and .for thereafter mailitaining them in such position during occupancy of the stretch, and occupancy v-irrdication means at vsaid forlioe governed by ysaid ,blockindication Arelay provided the contacts of .said .blok 'indication .repeater relayaie iii their normal positiimf .12. In a system of centralized trame control for stretch of track 'through 'which trafii'c .may 4move vin 'a given direction and :equipped with a code type communication system 'connecting the ends of :said stretch with a 'control olic,said'cod'e communication 'system `including at ythe entrance end of the strati-2h a starting yIclay -having "co'ntacts which .are moved .from a normal to an operated .position in Aresponse Ito :a change in apparatus conditions at said location 'and are 'restored to their normal position rin response to transmis- Asion of an indication code :from that location nto 'the Ionico, vin combination., a detector track `section 'at the entrance end of Said track stretch, `sai-d detector' track "section having attack circuit including fa ltrack relay., -ra system Yof circuits extending the length "of fsaifd' stretch fand governed Iby trafiic vconditions. in fsaid .stretch Aandfoontrolled from said pince through said code "com"- Arnutnication system to -at :times .prpare ksaid stretch `for tratlic insaid agivcn direction, a signaly at the entrance lend of said Astretch lgoverned said system Iof circuits', a, iblock relay at the `entrance Iend of said stretch, means :governed -by said system of `circuits for moving the block `relay Icontacts from their operated to their Inormal position when said system fof circuits prepares Said stretch' for traiiic and for thereafter maintaining said relay contacts in their operated position provided said stretch is vacant, a detector section repeater relay, means for said detector section repeater relay for causing its contacts to move from a normal to an operated position when the associated track relay releases, means for said detector section repeater relay for causing its contacts to move from their operated to their normal position when and only when the associated track relay is picked up and the oontacts of the associated starting relay are in their normal position, a block indication relay at said oice governed by said block relay through said code communication system, a block indication repeater relay at said office having contacts Which occupy an operated position when said stretch is not prepared for trafc, means governed through said code communication system by said detector section repeater relay and by said block relay for moving the contacts of said block indication repeater relay to their normal position in response to operation of said system of circuits to prepare said stretch for traffic in said given direction and for thereafter maintaining them in such position during occupancy of the stretch, and means governed by said block indication relay through said code communication system provided the contacts of said block indication repeater relay are in their operated position for v'causing said system of circuits to maintain traic in said stretch.

13. In a system of centralized traffic control for a stretch of single track railroad connected at the ends by track switches with adjacent passing sidings and equipped with a code type communisystem including at each end .of the stretch a starting relay having contacts which are moved from a normal to an operated position in response to a change in apparatus conditions at that location and are restored-to their normal position in response to transmission of an indication code from that location to the office, in combination, a detector track section at each end of the stretch including the associated track switch and provided with `atrack circuit including a, track relay,

Va system of reversible circuits extending the length of said stretch and governed jointly by traflic relays at opposite ends of the stretch so that at times the stretch is conditioned for trairlc movements in one direction and at other times for tra'ic movements in the other direction, a signal at each end of the stretch for governing traffic movements into the stretch, means for controlling each signal in accordance with the condition of said system of circuits, manually controlled electroresponsive means at said oiiice vfor designating the direction of trac movements in said stretch and controlling the transmission of control codes by said code communication system by which said traffic relays are operated to cause said system of reversible circuits to condition the stretch foi` one direction .of traffic or the other, each detector section track relay having associated therewith a detector section repeater relay, means for each detector section repeater relay for causing its contacts to move from a normal to an operated position when' the associated track relay releases, means for each detector section repeater relay for causing' its contacts to move from their operated to their normal position when and only when the associated track relay is picked up and the contacts of the associated starting relay are in' their'normal position, a block relay at each end of the stretch, means at each end of the stretch effective Vwhen the portion of said system of'freversible circuits for the portion of the stretch adjacent said end of the stretch prepares said stretch4 for traffic and indicates that such .portion ofthe stretch is unoccupied :for moving the contactsV of the associated blockrelay from their operated to their normal position, means for each;block relay'elective on movement of the contacts .of the associated detector section repeaterrelayto their operated Vposition provided the contacts *ofV said block relay are in their normal position and the associated trailc relay conditions that end of thestretch to be anentrance end for maintaining the contacts of said block relay in .their normal position, an auxiliary relay ai; the `:oillce having'contacts which occupy an'operated'position Whensaidstretch is not prepared for traiiic, means for movingthe contacts of said auxiliary relay to a normal position when indication-codes arev transmitted from both ends of the stretch with `the contacts of said lulockY relays inftheir normal position, and means at said officegoverned by said block relays through said lcode communication system. for controlling said electroresponsive traffic designating means provided the contacts of said auxiliary relay are in their normal position.

FRANK T. PASCOE.- ARTHUR L. JEROME.v

REFERENCES YCrriin rThe following references are of record: in 'the Number- Name 2,344,573 Van Horn Mar. 21, 1944 2,353,421 Staples Julyll, 1944 2,389,975 Hays ".r-- NOV. 27, v1945. 

